Manufacture of motor fuel



March lg, 46. 1 P JONES MANUFACTURE OF MOTOR FUEL Filed Dc'. 5, 1941recessed niet. te, ieee A dt af, il'i il 'if @F MTQR i .lean P. llaines,Bartlesville, 0.,

Phillips Petrole Company, a co Delaware Application December 5, 19411,Serial No. 21,822

2 C i (Cl. 26o-683.4)

This invention relates to the production of parcarbons khigherboilingpara :t hydrocarbons of ain hydrocarbons in the motor fuelboiling range high octane number. and of high octane number. It relatesmore parc Otherobiects and advantages of my invention ticularly to theproduction of such paraffin hydrowill become apparent to those skilledin the art carbons by the alkylation of lower boiling parfrom theaccompanying description and disaiiins, especially of low-boiling normalparamns, closure.

and theisomerization of hydrocarbon fractions of My invention 'will' nowbe more completely delow octane number so produced to produce parscribedin connection. with the drawing whichl ains of higher octane number.forms a -part of this application and which shows The alkylation ofisoparaiiins such as isobutane diagrammatically by means of a ow diagraman and isopentane with low-boiling olens produces arrangement ofapparatus in which my invention parain hydrocarbons in the motor fuelboiling `Will-he practiced together with various modicarange, which havehigh octane numbers and which tions thereof, said description alsoserving to exare suitable for use in premium motor fuels. Both emplifymy invention. catalytic and noncatalytic processes have been l5Referring now to the drawing, low-boiling parproposed to carry out suchalkylatioris and are weil amns such as a fractioncontaining asubstantial known to the art.v It has also been proposed to vduantityVoi normal butane is introduced through alkylate straight-chainparaiiinssuch as propane, pipe l@ controlled by valve it' to thealkylation normal butane, normal pentane', and certain parunit I2. Thealkylaton in unit l2 may be either ain hydrocarbon fractions of lowoctane number thermal or catalytic as previously stated and parin thelow part of the gasoline boiling range. The amns may be alkylated witholens or other alkyl.. alkylation of` such hydrocarbons can be carriedatingy reactants such as alcohols or alkyl halides out in the absence ofa catalyst at elevated preswhich may be introduced to the system throughsures and moderately elevated temperatures, and pipe it controlled by avalve ifi. may also be carried out in the presence of certain A When thealkylti rain iS promoted Calacatalysts under more moderate conditions.The lytically, the choice of a suitable catalyst depends catalysts whichhave been .proposed for such y somewhat'upon the alkylation reactants.For exalkylations include alkylation catalysts oi the ample, whenisoparaihn hydrocarbons are ai- 'metal halide type such as aluminumchloride or kylated with olefin hydrocarbons, especially gasealuminumbromide or combinations of these metal ous olefins, materials such asaluminum and zinc halides with other metal halides such as sodiumchlorides and bromides, an eduimolar mixture of chloride and the like,and also concentrated hysodium and aluminum Chloride (Sodium 6111010-drofluoric acid. In the alkylation of such paraluminate), boronfluoride, zirconium'chloride, amn hydrocarbons a substantial portionofthe and the like, concentrated sulfuric acid, and conproduct is of arelatively -low octane number. centrated hydrouoric acid maybe used assuit- However, such processes serve to convert large` able alkylationcatalysts. Of these catalysts, conamounts of hydrocarbon materials whichare too centrated sulfuric acid or hydrouoric acid is prevolatile fordirect inclusion in motor fuels into ierred, when the concentration ofisoparafn hyhydrocarbons which boil in the motor fuel range drocarbonsis relatively high, as they appear to and, therefore, iind a limiteduse. 40 promote the union of alkylating olei-lns with iso- I have nowfound that low-boiling straightparans more selectivelythan other knowna1- chain parain hydrocarbons can be converted to @lation catalysts, toproduce highly desirable hydrocarbons of high octane vnumber and in theproducts, while when there is little li any concenmotor fuel boilingrange by a combination of an tration of isoparailins and normal paramnsare alkylation step with a step for isomerizing certain @5 to be reactedpredominantly, aluminum chloride fractions separated from the effluentof the alkyla-f or bromide, sodium chloroaluminate, and other tion toproduce a composite motor fuel containing similar catalysts are to bepreferred, although hydrocarbons directly eiuent from the alkylationhydrouoric acid may also be used at higher` teme step blended withhydrocarbons which in addiperatures. tion t0 being formed by alkylationhave been 50 When alchols comprise the reactant for a1- isomerized.kylating parafllns in the presence of sulfuric acid An object of myinvention is to produce hydroor hydroiluoricacid, Water is formed as abyca'rbons in the motor fuel boiling range. product. Various reactionsmay occur in alkylator A further object of my invention is to produce l2when alcohols are the alkylatins reactant. but from low-boilingstraight-chain paraiiin hydrothe primary reaction is believed to bealkylation of paramns, especially parafiins having a tertiary carbonatom, which are more easily alkylated than other paraiiins. The primaryalkylation product appears to'undergo secondary reactions which formlower boiling and higher boiling products;

itprobablyv also undergoes isomerization. Prod v ucts especially usefulas motor fuels are obtained if the initial paraffin is an isoparafiinhaving four or flve carbon atoms'per molecule and if the alcohol hasthree .to ve carbon atoms'per molecule. However, the invention is not.tovbe necessarily limited to para-fllns and alcohols having thesenumbers of carbon atoms per molecule, for reactants with larger numbersmay be used.

When alkyl halides are used to alkylate parain fkhydrocarbons it hasbeen found that primary.

halides, especially ethyl halides, react relatively diicultly andrequire a catalyst more powerful than that which is adequate fornonprimary alkyl halides. Thus. when a primary 'alkyl halide. such asethyl chloride, is used. catalysts of the aluminumY chloride type aremore advantageous than catalysts of the sulfuricacid type." Alkylationof'i paraffin-hydrocarbons and especially isoparanln hydrocarbonswithalkyl halides takes place with an elision of a hydrogen halide, Whensulfuric acid or hydouoric acid is used. as the catalyst, the alkylationreaction appears to proceed most eiiiciently for isoparaiilns havingfour to eight carbon atoms per molecule and fornonprimary alkyl halidesin`which the alkyl group has three to six carbon atoms per molecule( Ofnonprimary alkyl halides, the tertiary react somewhat more.

rapidly than do the corresponding secondary al- .kyl halides, and theuse of an alkyl halide with a catalyst. such as sulfuric `acid appearsto give improved catalyst life as compared with theuse of thecorresponding olefin.

Ordinarily a process for the reactionlof al-U kylatable paraffinhydrocarbons with an alkylating reactant in the presence of analkylation cat- .alyst, such as sulfuric acid or hydroiiuoric acid,

is preferably operated under only moderate superatmospheric pressures,such as between about 20 and 200 pounds per square inch gauge. Since thealkylation reaction represents` a decrease in the total numberl ofmolecules, a certain amount of pressure favorsthe reaction. However,since the reactants are generally readily maintained in liquid phasewith only moderate pressure at the reaction temperature. in the lowerpart of the` range indicated, only sufficient pressure toinsure l liquidphase operation is generally adequate.

When higher reaction temperatures are used, higher pressures may also beused. and pressures as high as 1500 or .2000 pounds per square inch ormore may be used if desired. In most instances a catalytic alkylationprocess will be operated under a pressure between about and 500v poundsper-square inch gauge.

When sulfuric acid is the catalyst employed for the reaction ofalkylatable paraffin hydrocarbons with an alkylating reactant asdiscussed, the

concentration preferably should be maintained within the range of about90 to 102 per cent. ad-

vantageously above vabout 96 per cent. because the higher strengths ofacid promote the reaction of the more diflicultly alkylating reactantsas well as the difiicultly alkylatable parailins. Strengths vroutside ofthe range given downto about 80 per cent and up to about 105 per centmay be employed; however, when an olen is thel alkylatingreactantstrengths of sulfuric' acid so low as to promote excessiveolefin polymerization and so high as to cause excessive consumptionofthe acid, as in oxidation of organic materiahshould be avoided.Sulfuric acidcatalyst may be used at temperatures in the range .nuoricacid or hydrogen iiuoride, is very effecof 0 to 125 F., preferably atabout 30 to 70 F. The volurne ratio of hydrocarbon to sulfuric acid maybebetween about 1:3vand 5:1 and it is important that the reactants andacid be intimately admixed and emulsified. Generally, with extremelythorough intermixing, this ratio may be in the upper part of the range.It has been found' that a continuous intermixing of the reactants canvbe readily` accomplishedby lpassing them through acentrifugal pumpandthen through an elongated tube of a cross sectionl sufhciently retive.As discussed. the process is generally carried out with the hydrocarbonmaterial substantially in liquid phase; efficient reaction results whensuiiicient hydrouorlo acidis employed to result in a substantialsaturation of the liquid hydrocarbon material with hydrogen fluoride andpreferably sufficient hydrofiuoric acid is used to form a separateliquid phase which may be maintained and emulsied or intimately mixedwith' the hydrocarbon while reaction takes place'. In most cases thehydrofiuoric acid charge should be at least l0 per cent of the totalcharge, on a liquid volume basis, and hardly ever need exceed-50 to. 60per cent, though more can, at'times. be used. The reaction' temperaturewhen hydrofluoric acid is the alkylation catalyst may be varied over awide range for any particular reaction mixtureqbut appears to be mostdependent `upon'the paraffin hydrocarbon participating in the reaction.Thus, in general, I may carry out an alkylation process at temperaturesbetween about 0 and 300 or 400 F.. For readily reacted paraffinhydrocarbons, such as isobutane or isopentane, I may readily effect analkylatioh at a temperature between about 35 and 100 F. while for lessreactive paraiins, such as normal butane and normal pentane, highertemperatures are necessary or more desirable. The use of hydro- -fluoricacidhas a distinct advantage in such cases, in that it can be usedunderthese more extreme conditions without promoting or enteringintoextensive undesirable side reactions as is likely to occur whenconcentrated sulfuric acid is the alkylation catalyst.

The moleratio of alkylatable paraffin to al@ kylating reactant wheneither sulfuric acid or hydrofluoric acid is the alkylation catalystshould be at least 1:1 and is preferably higher. The mostl desirableresults are obtained when the mole ratio of alkylatable paraffin toalkylating reactant at the immediate zone of addition of the alkylatingreactant is not less than about 9:1. However, when particularly purehydrocarbons or a motor fuel stock of particularly high octane number,are desired the mole ratio of alkylatable paramn to alkylating reactantmayneedto be as high as 50:1 or 100:1 or even greater for any particularpoint at which alkylating reactant tions will be found when the moleratio of alkylatable parain to alkylating reactant is between 12:1 and100:1. Accordingly, multipoint addition of the alkylating reactant tothe reaction zone is advantageous, as in Frey 2,002,394, withoutintermediate fractionation or the like. as is known to the art.

When the reaction in unit l2 is conducted in the substantial absence ofa catalytic material which is active for the -promotion of an alkylationreaction, my process will be operated so that in-unit l2 a, highpressure thermal conversion of hydrocarbons is effected. My processbroadly includes any such process operating under a pressure in excessof 5 00 pounds per square inch, and preferably in excess of 1000 poundsper square inch. Such pressures may run as high as 10,000 to 15,000pounds per square inch or more depending somewhat on the strength of theapparatus, although generally pressures up to 5000 pounds per squareinch will be sufcient. In general, the temperatures will be between 750and l200 F., preferably 900 to 1000 F., and catalysts will not be usedexcept as the materials of the apparatus used may have an inherentfortuitous catalytic activity. The charge stock to such a thermalconversion step should contain only little, if any, methane,-

and while some pentanes or pentenes may be included in normally gaseousmixtures, large amounts of such material will 'generally not be treatedin this particular manner. The charge stock may be entirely paramnic, ormay contain unsaturated hydrocarbons, especially oleilns, and in somecases may comprise two separate hydrocarbon streams, one parailnic andone unsaturated, as illustrated in the drawing. In those cases whereonly a parafilnic hydrocarbon mixture is available and it is'desired tohave some unsaturated hydrocarbons present in the charge stock thedehydrogenation step as illustrated by unit 26 may be included in theprocess. Such a dehydrogenation step may be entirely thermal, or it maybe catalytic, or it may involve a 'combination of thermal and catalyticstepsl under known conditions.

The alkylation effluent passes through pipe i5 controlled by a valve I6to'separating means Il which will comprise various fractionatingcolumns, selective solvent extraction units, and associated equipment asmay be found convenient in any particular instance to effect theseparation of various fractions to be hereinafter discussed. ,In mostinstances the desired separations can be conveniently carried out by aseries of fractional distillation operations which will separate thealkylation product into a number of fractions, each of a relativelynarrow boiling range. Undesired low-boiling lmaterial will be dischargedfrom lthe system through a pipe 20 controlled by valve 2i. Low-boilingparaln hydrocarbons suitable for recycle to the system may be removedfrom the system by a pipe 22 controlled by a valve 23 and can berecycled to the system by being passed to pipe l0 by means not shown. Ifdesired a portion of this material, or a particular fraction oflow-boiling paramn hydro-- carbons, may be passed from pipe 22 through apipe 26 controlled by a valve 25 to the dehydrogenation unit 26 whereindehydrogenation takes place to produce oleiins suitable for use asalkylating reactants in the alkylation step. Low-boilingv parafns to bedehydrogenated may be introduced to the system through a pipe 2lcontrolled-by a valve 28 leading into pipe 2d. VDehydrogenation of highoctane number from a mixture containing hydrocarbons having the samenumber of carbon atoms per molecule but having a lower octane number,simple fractional distillation means will not always accomplish thedesired results in an' eflicient manner. In such instances an entrainingagent canbe empoyed in the separating means Il and so selected that itwill form a, constant boiling mixture or azeotrope-with at least onecomponent of the hydrocarbon mixture and when it is capable of formingan azeotrope with more vthan one component it preferably does so onlywith those components having either a high or low octane number. Byemploying fractional distillation of such a-hydrocarbon mixture in thepresence o f such an entraining agent, hydrocarbons of high octanenumber can ultimately be readily separated from hydrocarbons having thesame number of carbon atoms per molecule but having a lower octane'number. Entraining agents which are capable of promoting suchseparations comprise alcohols, esters, and organic acids having anappreciable vapor pressure in the boiling range of the hydrocarbons tobe separated. Specic examples of these agents include methyl alcohol,ethyl alcohol, furfural, glycol acetate, methyl formate, methyl acetate,ethyl acetate, and levulinic acid. Similar compounds will also producesimilar results and'those specified are only to be consideredillustrative. Such entraining agents are especially useful when it isdesirable to separate cyclic hydrocarbons from chain hydrocarbons-whenboth types have similar boiling points or boiling ranges but are notlimited to use with only such types.

One or more hydrocarbon fractions of high octane number are isolated inseparating means Il, in a suitable manner, such as discussed, and may berecovered as through pipes 40, 4l, and 42 controlled by valves 03, 44and t5, respectively. Any of these fractions may be recovered as anindividual fraction as shown or may be blended together to form acomposite motor fuel stock of high octane number. When this isdesirable, the fraction passing through pipe 40 may be removed therefromthrough a pipe 46 controlled by a valve 59, and to it may be added afraction fromv pipe 4I passing through pipe 49 controlled by a valve 48and/or a fraction passing y through pipe d2 which may be removedtherefrom through a pipe 50 controlled by a valve 5I, each of pipes 49and 50 passing to pipe il.

In a similar manner one or more fractions of low octane number may berecovered in separating means I1, in a suitable manner such asdiscussed, and passed to the isomerization step. Thus, a fraction may beremoved through a pipe 52 controlled by a Valve 53, and may bepasseddirectly to an isomerization unit ll for an isomerization treatment tobe described. However, it is generally desirable to ensure that thehydrocarbon material passed to the is'omerization unit Jl is essentiallyfree of reactive material, which bons, and I prefer to pass thefractions of low octane number through a treatment to remove suchnonparainic reactive material. This is conveniently done by means of anondestructive hydrogenation. When such a treatmentis to be included asa step in my process, the -material passing through pipe 52ispassedtherefrom through a pipe controlled by a valve 55 to anondestructive hydrcgenation unit 56. Hydrogen is used in such a unitand may be introduced into the system by a pipe 51 controlled by avalveI te. When thehydrogenation unit 58 is a part of my process,hydrogen recovered through pipe 33 may be introduced through pipe 51 forY use in this step of the process. One or more fractionsof low octanenumber recovered in separating means l1 may be removed therefrom throughone or more pipes represented by pipes tu and Si controlled by valves S2and 63, respectively, and introduced into pipe 54. When any of thesefractions may be introduced directly intol .the isomerizaiton stepwithout treatment to revtraction, polymerization or the like, as may bebest suited in any particular case. The concentration of such reactivematerial will generally not be very high, and when nondestructive hy-ldrogenation is used, this may be carried out under a. slightsuperatmospheric pressure in the presence of any non'destructivehydrogenation catalyst such as active nickel supported on an inertsupport. The effluent of the hydrogenation is passed through a pipecontrolled by a valve ous material is removed through apipe 13controlled by a valve 14, and an essentially parainic material isrecovered through a pipe 15 and Y passed to an isomerization unit 11through valve I* The material entering isomerization unit 11 throughpipe 15 may be joined by any material which is passed directly to theVisomerization unit through 52. Such material may be supplemented by aparaiiinie fraction of low octane number in the motor fuel boiling rangefrom any suitable source not shown and passed to the system through apipe 18 controlled by a valve 19 leading to pipes 52 and 15. Anyundesired portion of the material passing from separating means 12through pipe 15 may be removed from the system through pipe 80controlled by a valve 8i.

-When any material of low octane numbenwhioh is to be charged to theisomerization stepV from an outside source,lcontains small amounts of.nonparailnic reactive material, such as unsatuated under continuousconditions and either in liquid, mixed, or vapor-phase as may bedesirable or expedient in view of the particular hydrocarbon orhydrocarbon mixture. undergoing treatment and dependent on theparticular isomerization catalyst employed. The isomerization in unit 11can-be carried out on any of the normal paraiiin hydrocarbons havingfour or more car- -bon atoms per molecule and preferably those whichboil at a temperature not greater than about 320 F. Suitable paramnhydrocarbons are normal butane. normal pentane, normal hexane, normalheptane, and particularly those hydrocarbons in the motor fuel boilingrange and having a low octane number. In someinstances naphthas may betreated in the lisomerizatioiu zone and especially virgin naphthascontaining large amounts oi' normal paramn hydrocarbons. Such naphthaswill be passed to the Aisomeriza tion unit 11 by means of conduit 18controlled by valve 19.

Isomerization unit 11 can be operated to isomerize a substantially purenormal paramn hydrocarbon or a mixture comprising a plurality of suchhydrocarbons. In some instances it will be desirable for unit 11 tocomprise several separate isomrization elements, the charge stock t0each element comprising a Asubstantially pure isomerizable paraiiinlhydrocarbon and each element operated under such conditions as topromote the isomerization of said isomerizable paraiiin hydrocarbon toan optimum degree. The isomerization in unit 11 is preferably carriedout in the presence of an isomerization catalyst of the aluminum halidetype although the halides of arsenic, tungsten, molybdenum, zinc, iron,cadmium, beryllium, antimony, tin, zirconium, or. boron. either alone orin admixture, may rind application in some instances. In general,however, I

4 have found that the aluminum halide type of rated hydrocarbons orsulfur compounds, and

pure material is purified by hydrogenation it may be charged directly tothe hydrogenation unit 5B, as by being passed through pipe 51 along withl the free hydrogen.

The isomerization'unit 11 is preferably operl catalyst is most desirablein my process. How- 1l to a separating means 12. Low-boiling gaseever,in the broadest aspects of the case I am not specifically limited tooperate solely in the presence of such a catalyst.

Practically suitable catalysts are .aluminum chloride and aluminumbromide and I will describe the operation of my process when operlatingin the presence of such a catalyst; The aluminum halide may beusedby itself or in association with other catalytic or promoting agents.such as ferrie chloride or bromide, halo` in somewhat greater quantity,for example from two to live per cent by weight. Also one ormore suchsuitable aluminum halide catalysts may be-l mixed with or deposited onfiller or supporting materials such as activated charcoal, silica ygel,or bauxite, or other materials such as pumice. kaolinites, vmeerschaum.kieserite. or the like.

When operation in the liquid phase is desired. the hydrocarbon'materialto be treated and the aluminum halide catalyst may be charged to asuitable reaction vessel in isomerizationunit 11 in the desired relative.amounts and the mixture maintained atthe desired temperature for a time.necessary to eilect the desired extent of isomerization. The relativeproportions of the' catalyst andthe hydrocarbon material to be treatedmay vary over a comparatively wide rangeyand will, in general, dependupon the particular catalyst used. upon the particular hydrocarbonmaterial to be treated, and upon the speclc temperature and contact timeemployed. An aluminum halide catalyst may be advantageously employed inan amount equal to from about one per cent to about fteen per cent byweight of the hydrocarbon material treated at any one time. At lowtemperatures and long contact times, as discussed herein, the amount ofaluminum halide present in the isomerization zone 'may vary betweenabout per cent and 150 per cent, or even greater, by weight of thetotalI hydrocarbon in the isomerization chamber at any one time. In suchinstances the preferred aluminum halide concentration is generallybetween about 100 per cent and about 150 per cent by weight. In general,however, the

hydrocarbon to be treated is present in relatively great excess over thecatalyst. When desirable, a gaseous' hydrocarbon or hydrocarbon mixturemay be contacted with the catalyst.- This may be done in a variety ofsuitable manners.

For example, when the catalyst is in the form of When using an aluminumhalide-type catalyst, or similar catalyst, there should also be presenta substantial amount of a hydrogen halide, preferably one correspondingtothe aluminum halide beingused. Such a. hydrogen halide, or mixture ofhydrogen halides, may be added to the reaction vmixture in the desiredamount in any convenient manner.

The reactions in isomerization unit 11 are generally carried out under apressure suiciently high to ensure the presence of a liquid phase in theunit and in the presence of such an amount of a hydrogen halide that thepartial pressure of the hydrogen halide in the unit i's equal to atleast about ve pounds per square inch.I Total pressures of from about 10to about 100 pounds per square inch are preferred and they may be ashigh as 300 atmospheres or higher. Higher presmotor fuel: boiling rangecan be converted to higher octane number hydrocarbons at a` lowertemperature than lower boiling isomerizable paraflin hydrocarbons can beconverted. i

- Although as has been stated, the isomerization' reaction willgenerally take place in the liquid phase there are instances where vaporphase operation is preferable. For the isomerization of normal butane,operation in the vapor phase is sonietimes preferred while with the Thecatalyst may be either in the form of a slurry or adsorbed VYon asupport. Higher temperatures are usually unnecessary and areAundesirable 'in liquid phase operation due to the higher operatingpressures and more expensive equipment necessitated.

The isomerization step, in either the liquid or vapor phase, may beconducted over a wide range of contact times of the material to betreated with the catalyst under the reaction conditions. The mostsuitable contact time will depend upon the particular catalyst, theparticular reaction conditions such as temperature and pressure andsures appear to favor isomerization reactions, but

also result in the necessity for handling large amounts ofnonhydrocarbon material, thereby necessitating larger equipment. Ifdesired, relatively inert diluent gases such as hydrogen, nitrogen,carbon dioxide, methane, ethane, and the like may be introduced into theisomerization unit l1.

Ihe isomerization step is conducted at a temperature not greater thanabout 400 F. and preferably at temperatures below about 320 F. Attemperatures greater than about 400 F. losses of material due toundesirable cracking reactions are prohibitive. The lower limit of thetemperature range is set'by the temperature at which the desiredisomerization will take place at apractical rate. Temperatures as low as20 F. may in some cases be used, but only a very slow reaction rate cangenerally be obtained. A suitable practicable operating range is fromabout 120 F. to about 320 F. Generally, the higher temperatures areemployed for the isomerization of normal parain hydrocarbons of lowermolecular weight. That is, for example, all other conditions beingequal, normal pentane can be isomerized at a lower temperature thannormal butane and low octane number hydrocarbons in the upon the natureand composition of the material to be isomerlzed. 1n any case, thecontact time is so chosen with respect to other factors that thedecomposition and/or cracking of the resultant product is substantiallyobviated.. Higher temperatures of operation usually require lowercontact times than lower temperatures of operation. Also, Vapor phaseoperation may require a lower contact time than liquid phase operation.This is duein part, to the fact that vapor phase operation is usuallyconducted at a higher teinperature range than liquid phase operation.Vapor phase isomerization of normal butano to isobutane, for example, attemperatures of from 120 F. to about 320 F. inthe presence of aluminumchloride catalyst requires contact times of from about 10 to about 200seconds. 'For liquid phase operation in` the presence of aluminumchloride catalyst the time of contact will vary considerably ,forconverting normal butane to isobutane and will range from about 1 to 150minutes and may range as high as from 30 minutes to 30 hours in thetemperature range between 30 and250," F. Furthermore, isomerization ofhigher molecular weight hydrocarbons, such as the conversion of lowoctane number hydrocarbons in the motor fuel boiling range to higheroctane number motor fuel hydrocarbons, generally requires a lowercontact time, other condil conditions discussed may be regenerated inany conventional manner well known to the art after vwhich theregenerated catalyst can again be em- 6 ever, it is not desirable toregenerate such a spent isomerization catalyst such a spent catalyst maybe advantageously employed in a catalytic alkylation step, such as isconducted, in unit i2 of my process. oftentimes material, such as aspent aluminum halide, which will be obtained in an oily lform combinedin a complex compound with hydrocarbon material and which is no longeractive for promoting isomerization reactions can be used as a catalystfor the union of amlatable hydrocarbons with an alkylating reactant and.I contemplate so operating when it is desirable The eiiiuent of theisomerization unit 'il is passed therefrom through a pipe 82 controlledby a valve 83 to separating meanssfl which will in clude suitablefractionating columns. scrub .unitsl filters, and the like, togetherwith associated equipment to effect the desired separation andpurication of one or more hydrocarbon fractions of high octane numberboiling in the motor fuel range. Light gases may be discharged from. thesystem through a pipe 85 controlled by a valve 8B. Tars, catalystsludge, and the like, may be discharged from the system through pipe 8lcontrolled by a valve 88. A hydrocarbon fraction of high octane numbersuitable for use as a motor fuel stock 4is separated throughfa pipe 8@'con-f trolled by valve 9|., and may be passed directly tol pipe 4'! andrecovered as a product of the process. In some instances especially witha ilmited extent of isomerizatlon one or more fractions of low octanenumber may be passed from separating means 84 through pipe 82 and 'valve93 to pipe .15 for retreatment in the isomerization step. A portion ofsuch a recycle stock may be removed from the system by being passed frompipe,92 through pipe 94 controlled by a valve 9S.

' Low-boiling hydrocarbons, which may include isobutane and/orisopentane, may be passed from separating means 84 to the alkylationunit i2 through pipe 96 controlled by a valve 9i.

It will be appreciated thatl in connection with the actual operation ofany modification of my process much conventional equipment not shown intheflow diagram of the drawing may need to be used and may be readilysupplied by one skilled in the art. Such equipment will include pumps.heaters, coolers, catalyst chambers, fractionating columns, refluxlines, temperature controllers, and the like. Such equipment may beadapted in any particular case by one skilled in the art with thebenefit of the discussion and .disclosure of l,the operating conditionsand material ows asoaess oi 500 pounds per square inch and in theabsence j of a catalyst to form a mixture of alkymers comprising highoctane number and low octane number paraiiln hydrocarbons boiling in themotor fuel range and formed by said alkylation, separating from saidmixture a first fraction comprising so-formed high octane numberalkymers boiling in the motor i'uel range, separating also from saidmixture a' second fraction comprising so'- formed alkymers having thesame number of carbon atoms per molecule as those of said first fractionbut having a lower octane number, subjecting saidv second fraction tonon-destructive hydrogenation to produce a low octane number ailnvlnerfraction essentially free of non-paraffinic material, subjecting theresulting saturated fraction to isomerization in the presence of anisomerization catalyst of the metal halide type under conditionsavoiding cracking to form high octane'number isomers of said alkymers'solely by isomerization of said low octane number alkymers, separatingfrom the eiiiuentlof said isomerization a high octane number fractioncomprising said isomerlzed alkymers, and blendingthe last said fractionwith the aforesaid first fraction to form as a product of the process acomposite paraiiinic motor fuel stock of high ocnormally gaseousalkylatable straight-chain par- -arnns with said lower-boiling normallyVgaseous oleiins at a temperature between 750 and 1200"' F. and apressure in-excessof 500 pounds per square inch and in the absence of acatalyst to form a mixture of alkymers comprising high octane number andlow octane'number paranln hy- Y drocarbons boiling 'in the motor fuelrange and .fraction to non-destructive hydrogenatlon to.

formed by said alkylation, separating from said mixture a iirst fractioncomprising so-lormed v high octane numb'er alkymers boilingin the mo-"ytor fuel range, separating also from said mixture a second fractioncomprising so-formed alkymers having the same number of carbon atoms perv molecule as those of said iirst fraction but having' a lower octanenumber, subjecting said second produce a low octane number -alkymerfraction between '150 and 1200 F. and a pressure in excess vessentiallyfree of non-paraffinic material, subjecting the resulting saturatedfraction to isomerization in the presence of 'an isomerization catalystof the metalhalide type under conditions avoiding cracking to form highoctane number isomers of said alkymers solely by isomerization of saidlow octane number allgvmers, separating from the eiiluent of saidisomerization a high octane number fraction comprising said isomerizjedalkymers, and blending the last said fraction with the aforesaid firstfraction to form as a product v of the process a composite paraiiinicmotor fuel stock of high octane number. Y

` JEAN P. JONES.

